Safety book for furnaces



June 15, 1948.

H. WEYENB ERG EI'AL SAFETY DOOR FOR FURNACES Filed July 8, 1944 H 12??? V 7 ,7 6 er 1% 2 16 13 Q BY 6 1? Patented June 15, 1948 SAFETY DOOR FOR FURNACES Henry Weyenberg and Walter R. Kimberley, Holland, Mich., assignors to Holland Furnace Company, Holland, Mich., a corporation of Dela- Application July 8, 1944, Serial No. 544,063

8Claims. (01410-475) This invention relates to furnaces, including those employing coal designed for either hand firing or stoker feeding, and those employing oil as a fuel with various types of burners therefor. It is concerned with a safety valve device applicable to any such furnace, for relieving temporary gas pressure therein due to incomplete or spasmodic combustion.

One of the objects of the invention is to provide a new and improved safety valve or door, for the purpose indicated, which shall be economical to manufacture and simple to operate.

Another object of the invention is to provide a safety door or valve for a furnace having included therein a sight opening or window and a shutter for such opening.

It is also an object of the invention to provide a, safety door mounted to open automatically in response to excessive gas pressure inside a furnace, and fitted with manually adjustable means for holding it in open position to provide the furnace with additional air for combustion continuously.

, More specifically, it is an object efthe invention to provide a safety valve for furnaces in the form of a door hinged to open outwardly and biased yieldingly to closed position, said door having an inspection window and a shutter for the window movably mounted on the inner face of the door and arranged to operate a cam device for propping the door open more or less widely at various positions of adjustment of the shutter.

' Other objects and advantages of the invention will appear from the following description taken in connection with the drawings in which Fig. 1 is a somewhat diagrammatic sectional view of the upper portion of a furnace indicating the position at which the safety door embodying this invention is applied thereto.

Fig. 2 is a fragmentary front elevation of the fuel feeding door of the furnace, showing the safety door or valve mounted thereon and at open position.

Fi 3 is a vertical sectional view taken as indicated at line 3-3 on Fig. 2.

Fig, 4 is a horizontal sectional view taken as indicated at line 4-4 on Fig. 2.

Fig, 5 is a fragmentary rear elevation of the safety door showing the cam on the shutter of the inspection window.

While we have shown in the drawings and have herein described in detail a preferred form of our invention, it is to be understood that we do not intend to limit the invention to the specific charging door posed respectively. above and below form or application disclosed, but aim to cover all modifications and alternative constructions falling within the scope of the invention as ex pressed in the claims.

For purposes of illustration, Fig. 1 shows the general outlines of the upper portion of a warm air heating furnace including the outer Jacket I and the combustion chamber 2 which acts as a heat radiator to transfer heat to the air which circulates between the outer jacket and the combustion chamber. The view omits the lower portion of the furnace Which'usually contains the grate bars, but shows the smoke outlet at 3 with a battle 4 associated therewith and shows the forwardly extending flange 5 which surrounds the fuel charging pening of the combustion chamber 2 at the forward side. This flange extends through the front Wall of the outer jacket l and supports a frame 6 to which the fuel charging door 1 is hinged in the usual manner. Thus, the door 1 becomes a portion of the outer Wall of the combustion chamber 2. In earlier types of furnaces the accumulation of coal gas in the combustion chamber 2 and its explosive ignition often caused the charging door 1 to be blown open, releasing gas and smoke and occasionally flames which caused a fire hazard. If this occurred without knowledge of the occupants of the building, the resulting damage might be serious and in any event with the charging door left standing open the draft would tend to be impaired, causing the fire to die out, Accordingly, the door 1 is shown equipped with a small safety door 8 which normally closes an opening 9 in the door 1. The flange l0 outlining the opening 9 terminates in a plane slightly inclined to the vertical so that the door 8, being suspended by hinge pivots H, is yieldingly biased by gravity to its closed position. Thus, in the event of excessive gas pressure or explosion in the combustion chamber 2 the safety door 8 swings outwardly and the pressure is immediately relieved through the opening 9, but the door 8 closes again as soon as the pressure returns to normal.

Fig. 2 shows a fragmentary portion of the 1 with the safety door 3 hinged thereto. The door 8' is shown at partially open position so that the lower portion of the flange It and a small area of the opening 9 are visible. For inspecting the condition of the fire at any time it is desirable to have a small sight opening or window, and the safety door 8 provides aconvenient location for such a window. As shown, it consists of two segmental openings l2 and I3 disa pivot M on which a shutter I is carried for normally closing the windows 12 and I3. The shutter I5 is mounted on the rear of the door 8 with its upper and lower portions normally overlapping the openings l2 and I3, and the shutter is provided with a finger piece It which projects through the upper window l2 to permit the shutter to be rotated manually to open position for inspecting the condition of the fire.

As a feature of the present invention, the rotatively movable shutter member I5 is made to perform an additional function. For certain types of fuel it is frequently found necessary to provide secondary or additional air over the fuel bed to insure complete combustion. For example, with a good grade of Pocahontas coal a very slight addition of air might be sufiicient, whereas with a relatively soft coal a considerably larger proportion of additional air would be required over the fire to result in reasonably complete combustion. This additional air may be supplied through the door 8 by providing means for propping the door in open position and, preferably, making such means adjustable to vary the quantity of air thus admitted. For this purpose the lower portion of the shutter i5 is provided with a cam H in the form of an arcuate flange projecting inwardly or rearwardly from its lower edge to engage with a lug is extending upwardly from the flange ill which frames the safety door opening 9. As shown, the lug I8 is formed with a recess or depression l9 and the flange H which is of graduated height from end to end is formed with three points or projections Fla, Nb and Ho positioned to rest in the recess IQ of the lug l8 successively as the cam H is turned by rotation of the shutter member ill with which it is integral. Thus, by rotatively adjusting the shutter 45 to bring either the point Ha, l'lb or l'lc into the recess IQ of the lug Hi, the safety door l8 may be propped open at any one of three diiferent angles to afford the desired additional air to the fire for supporting combustion Since the purpose of this adjustment is to admit air through the opening, the fact that the inspection windows l2 and 13 are opened incidentally in adjusting the door 8 to open position will not interfere with the desired result. The cam H is so designed that the windows 12 and 13 are opened only a little way when the point Ila of the cam ll engages the lug 18 for providing a minimum opening of the door 8; further rotation of the shutter l5 and the cam 11 increases the opening at the windows 12 and t3 and simultaneously increases the amount by which the door 8 is opened.

Thus, instead of providing an additional valve or door to supply supplemental air to the fire and providing a separate mechanism for adjusting such additional door or port to meet various conditions we employ the adjustable shutter of the inspection windows l2 and it to actuate a cam which in turn adjusts the safety door 8 at a series of positions to meet all the requirements.

In some furnaces it is found desirable to supplement the safety door with a'baflle plate fixedly mounted at the inner side of the wall or door in which the safety door is installed. Such a baffle plate is shown at -20 in Figs. 3 and 4, being supported in spaced relation to the inner face of the door I. The inner face of the door may be proviti'ed with integral bosses 2] on which the baiil'e plate 20 is lodged, and a pair of bolts 22 disposed adjacent these bosses will furnish suffisaid shutter to swing An observacenter of the it to permit 4 cient securement for the plate ac. tion port 23 is formed at about the plate opposite the windows if and inspection of the fire.

The presence of the plate 2b tends to retard the velocity of the incoming air admitted when the safety door is open and prevents it from interfering with flame propagation in the fire pot, while at the same time admitting the additional oxygen required for proper combustion and tending to distribute the additional air from the spaces adjacent the edges of the plate 20 as well as from the opening 23 therein. As shown in Figs. 1 and e the panel which constitutes the door 1 has a marginal flange forming a concave surface la extending around the edge of the door so that the air admitted from between the marginal portions of the plate 29 and the inner face of the door panel will be deflected inwardly toward the fire but without excessive velocity, and will be well distributed for assisting combustion.

We claim as our invention:

1. In a furnace structure which includes a combustion chamber and an outer wall having an opening, a safety door hinged to said wall in position to cover said opening, said door being hinged to swing outwardly and being yieldingly biased to closed position, said door having an inspection window for observation of the fire in the chamber, a shutter normally covering said window, said shutter being movably mounted on the door and adjustable at will to uncover the window, and a cam operable by movement of the door bodily outward upon its hinge,

2. In a furnace structure which includes a combustion chamber and an outer wall having an opening, a safety door hinged to said wall in position to cover said opening, said door being hinged to swing outwardly and being yieldingly biased to closed position, said door having an inspection window for observation of the fire in the chamber, a shutter normally covering said window pivotally attached to the door and rotatively adjustable at will upon its pivot to uncover the window, and a cam operable by the rotation of said shutter to swing the door bodily outward upon its hinge.

3. "in a furnace structure which includes a combustion chamber and an outer wall havin an opening, a safety door hinged at its upper edge in position to cover said opening, the opening being disposed in a plane inclined outwardly and downwardly and said door being hinged to swing outwardly from the opening and being biased by gravity to closed position, said door having an inspection window for observation of the fire in the chamber, a shutter normally covering said window and movably mounted on the door for adjustment at will to uncover the window, and a cam projecting from the inner "side of the door and operable by the movement of the shutter to hold the door open.

4. In a furnace structure which includes a combustion chamber and an outer wall having an opening, a safety door hinged at its upper edge in position to cover said opening, said door being hinged to swing outwardly and being biased by gravity to closed position, said door having an inspection window for observation of the fire in the chamber, a shutter normally covering said window pivotally attached to the inner face of the door and rotativefy adjustable at will upon its pivot to uncover the window, and

a cam integral with the shutter and operable by rotation thereof to swing the door bodily outward upon its hinge.

5. In a furnace structure which includes a combustion chamber and an outer wall having an opening, a safety door hinged at its upper being hinged to swing outwardly and being biased by gravity to closed position, said door having an inspection window for observation of the fire in the chamber, a shutter normally covering said window pivotally attached to the inner face of the door and rotatively adjustable at will upon its pivot to uncover the window, and a cam formed as a flange projecting from the inner face of the shutter and of graduated height, said flange engaging a fixed portion of the said wall when the shutter is rotated upon its pivot and thus operating to swing the door bodily outward upon its hinge.

6. In a furnace structure which includes a com ustion chamber and an opening, a safety door hinged at its upper edge in position to cover said opening, said door being hinged to swing outwardly and being biased by gravity to closed position, said door having an inspection window for observation of the fire in the chamber, a shutter normally covering said window pivotally attached to the inner face of the door and rotatively adjustable at will upon its pivot to uncover the window, and a cam formed as a flange of graduated height projecting from the inner face of the shutter and concentric with respect to the pivot thereof, the said said door having an inan outer wall having the door and adjustable at will to uncover the window, and means operable by movement of said shutter to swing the safety door bodily routwardly upon its hinge means.

8. In a furnace structure which includes a combustion chamber and an outer wall having an opening, a safety door hinged at its upper edge in position to cover said opening, the opening being disposed in a plane inclined outwardly and downwardly and said dOOr being hinged to swing outwardly from the opening and being biased by gravity to closed position, said door havin an inspection window for observation of the fire in the chamber, a shutter normally cov ering said window and movably mounted on the door for adjustment at will to uncover the window, and means operable by movement of said shutter to swing the safety door bodily outwardly upon its hinge means.

HENRY WEYENBERG. WALTER R. KIMBERLE'Y.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 105,167 Burleigh July 12, 1870 197,161 Musgrave et a1 Nov. 13, 1877 542,280 Renfroe July 9, 1895 590,431 Gope Sept. 21, 1897 615,599 Wewers Dec. 6, 1898 643,886 Ormerod Feb. 20, 1900 711,653 Burdick Oct. 21, 1902 731,235 Sidaway June 16, 1903 737,105 Horvath Aug, 25, 1903 939,996 Fortune Nov. 16, 1909 1,427,483 Kurtz Aug. 29, 1922 1,470,309 Wimmer Oct. 9, 1923 1,653,401 Johnson Dec. 20, 1927 1,717,658 Bryant June 18, 1929 1,765,828 Doyle June 24, 1930 2,043,808 Norton et a1 June 9, 1936 2,064,064 Hunker Dec. 15, 1936 FOREIGN PATENTS Number Country Date 18,951 Great Britain of 1902 656,887 France Jan. 7, 1929 

